Reduced graphene oxide loaded high-entropy oxide as well as preparation method and application thereof

Abstract

The invention discloses a reduced graphene oxide loaded high-entropy oxide as well as a preparation method and application thereof, and the preparation method comprises the following steps: respectively dissolving graphene and metal salt in respective solvents for ultrasonic treatment to respectively obtain a metal salt solution and a graphene suspension; adding a metal salt solution into the graphene suspension, adding urea, stirring, and then pretreating the obtained mixed solution to obtain precursor powder; and performing plasma flow treatment on the precursor powder to obtain the reduced graphene oxide loaded high-entropy oxide. The high-entropy oxide prepared by the preparation method has the advantages of multi-crystal face scattering, excellent impedance matching performance and strong wave-absorbing loss capability, and has a wide application prospect in the electromagnetic fields of consumer electronics, new energy vehicle-mounted and military weapons.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and particularly relates to a high entropy oxide loaded with reduced graphene oxide, a preparation method and an application thereof. Background Art

[0002] With the commercialization of 5G technology and the booming development of artificial intelligence, electronic devices that carry electromagnetic waves are widely used in fields such as communications, medical care, and energy, and they accompany people's entire lives. Although high-frequency communication technology provides great convenience for the efficient transmission of information, its densely distributed electromagnetic radiation seriously interferes with the normal operation of equipment and endangers human health. High-entropy oxides are expected to be used as new electromagnetic absorbers in the fields of electronic communications and aerospace military due to their adjustable dielectric properties and rich lattice defects.

[0003] The high-entropy oxides synthesized at present are basically irregular in shape due to long-term crystallization at high temperature, and their particles tend to agglomerate into blocks. The input impedance and dielectric parameters of the material are basically adjusted by the composition and content of the high-entropy oxides. It is difficult to control the electromagnetic properties of the high-entropy oxides by using microstructure. In addition, the electromagnetic attenuation ability of single-phase high-entropy oxides is limited, and additional phases need to be added to form heterogeneous composite materials to meet the needs of electromagnetic absorption. Summary of the invention

[0004] (I) Purpose of the invention

[0005] The purpose of the present invention is to provide a high-entropy oxide loaded with reduced graphene oxide, a preparation method and an application thereof. The high-entropy oxide obtained by the preparation method of the present invention has the advantages of polycrystalline surface scattering, excellent impedance matching and strong wave absorption loss capability, and has broad application prospects in the electromagnetic fields of consumer electronics, new energy vehicles and military weapons.

[0006] (II) Technical solution

[0007] To solve the above problems, the first aspect of the present invention provides a method for preparing a high entropy oxide supported by reduced graphene oxide, comprising the following steps:

[0008] S1, dissolving graphene and metal salt in respective solvents and subjecting them to ultrasonic treatment to obtain metal salt solution and graphene suspension respectively;

[0009] S2, adding the metal salt solution to the graphene suspension, adding urea and stirring, and then pretreating the resulting mixed solution to obtain a precursor powder;

[0010] S3, subjecting the precursor powder to plasma flow treatment to obtain a high entropy oxide supported by reduced graphene oxide.

[0011] Furthermore, in the step S2, the mass ratio of graphene, metal salt and urea is controlled to be 1:(1-10):(5-50).

[0012] Furthermore, the metal salt is a soluble metal salt, including iron salt, cobalt salt, nickel salt, copper salt and manganese salt.

[0013] Furthermore, the pretreatment includes centrifugation, washing and freeze-drying in sequence.

[0014] Furthermore, in the step S3, the processing time of the plasma jet is 0.5 to 10 s, and the current is 30 to 60 A.

[0015] Furthermore, the electrical conductivity of the high entropy oxide is 0.45-10 S / cm.

[0016] The second aspect of the present invention provides a high entropy oxide supported by reduced graphene oxide, wherein the high entropy oxide is obtained by any one of the methods for preparing a high entropy oxide supported by reduced graphene oxide described above, and the structure of the high entropy oxide includes tetrahedron, octahedron and truncated octahedron.

[0017] Furthermore, the particle size of the high entropy oxide is 50 to 250 nm.

[0018] Furthermore, the high entropy oxide includes iron, cobalt, nickel, manganese and copper, and the high entropy oxide particles account for 10% to 30% of the total mass.

[0019] In addition, the third aspect of the present invention provides an application of a high entropy oxide supported by reduced graphene oxide as described in any one of the above descriptions or a high entropy oxide supported by reduced graphene oxide prepared by the preparation method described in any one of the above descriptions in the electromagnetic field.

[0020] (III) Beneficial effects

[0021] The above technical scheme of the present invention has the following beneficial technical effects: the present invention provides a high entropy oxide supported by reduced graphene oxide, a preparation method and an application thereof, the high entropy oxide obtained by the preparation method of the present invention, the particles of which are uniformly supported on the surface of the reduced graphene oxide and there is no particle agglomeration, so that the impedance matching is enhanced, the structure of the high entropy oxide is a polyhedron, and the polycrystalline surface structure enhances the multiple scattering of electromagnetic waves. The preparation method process is: first prepare a metal salt solution and a graphene suspension, then add the metal salt solution to the graphene suspension, add urea and stir, then pre-treat the obtained mixed solution to obtain a precursor powder, and finally treat the precursor powder with a plasma flow to obtain a high entropy oxide supported by reduced graphene oxide, and the high entropy oxide supported by reduced graphene oxide prepared by the present invention has the advantages of polycrystalline surface scattering, excellent impedance matching, and strong wave absorption loss ability, and has broad application prospects in the electromagnetic fields of consumer electronics, new energy vehicles and military weapons. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a transmission electron microscopy image of a high entropy oxide supported by reduced graphene oxide obtained in Example 1 of the present invention;

[0023] Figure 2 This is a high-resolution electron microscopy image of the high-entropy oxide supported by reduced graphene oxide obtained in Example 1 of the present invention;

[0024] Figure 3 is an energy spectrum of the high entropy oxide supported by reduced graphene oxide obtained in Example 1 of the present invention;

[0025] Figure 4 It is a comparison diagram of the conductivity of high entropy oxide supported by reduced graphene oxide prepared in Example 1, Example 2, and Example 3 of the present invention;

[0026] Figure 5 This is a graph of electromagnetic absorption loss of high entropy oxide supported by reduced graphene oxide obtained in Example 1 of the present invention;

[0027] Figure 6 is a transmission electron microscopy image of the high entropy oxide supported by reduced graphene oxide obtained in Example 2 of the present invention;

[0028] Figure 7 This is a high-resolution electron microscopy image of the high-entropy oxide supported by reduced graphene oxide obtained in Example 2 of the present invention;

[0029] Figure 8 is an energy spectrum of the high entropy oxide supported by reduced graphene oxide obtained in Example 2 of the present invention;

[0030] Fig. 9This is a graph of electromagnetic absorption loss of high entropy oxide supported by reduced graphene oxide obtained in Example 2 of the present invention;

[0031] Fig.10 is a transmission electron microscopy image of the high entropy oxide supported by reduced graphene oxide obtained in Example 3 of the present invention;

[0032] Fig.11 This is a high-resolution electron microscope image of the high-entropy oxide supported by reduced graphene oxide obtained in Example 3 of the present invention;

[0033] Fig.12 is an energy spectrum of the high entropy oxide supported by reduced graphene oxide obtained in Example 3 of the present invention;

[0034] Fig.13 This is a graph of the electromagnetic absorption loss of the high entropy oxide supported by reduced graphene oxide obtained in Example 3 of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific implementation methods and with reference to the accompanying drawings. It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the functional differences of components as the criterion for distinction. As mentioned in the entire specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not used to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0036] As a typical two-dimensional carbon material, graphene has a large specific surface area, excellent electrical conductivity and high stability. At the same time, graphene can provide anchoring points when high entropy oxide crystallizes to avoid particle agglomeration. Therefore, it is of great significance to develop a simple and efficient method for preparing a high entropy oxide supported by reduced oxide graphene with a polyhedral structure. To this end, the first aspect of the present invention provides a method for preparing a high entropy oxide supported by reduced oxide graphene, comprising the following steps:

[0037] S1, dissolve graphene and metal salt in respective solvents and ultrasonically treat them to obtain metal salt solution and graphene suspension respectively. The treatment of graphene is as follows: graphene is used as the source of reduced graphene oxide in the final reduced graphene oxide loaded high entropy oxide, and the graphene can be any commercially available one, preferably any one or more from Shanghai Aladdin, Titan Technology, and Xiamen Kaina. The solvent is any one or more of water, ethanol, methanol, and isopropanol, preferably water. The mass volume ratio of the graphene to the solvent is (0.25-1.5): 1, preferably (0.25-0.75): 1, and more preferably 0.5: 1, in mg / mL. Ultrasound refers to the dispersion of the graphene solution using an ultrasonic cell disruptor, the working efficiency of the cell disruptor is 20-1000W, preferably 300-500W, and more preferably 400W, and the ultrasonic time is between 45-150min, preferably 60-90min, and more preferably 60min. The unique cavitation effect, mechanical effect and thermal effect of ultrasound are used to form local high temperature and high pressure in the solvent accompanied by jet flow, so as to promote the uniform dispersion of graphene in the solvent to form a graphene suspension. The treatment of metal salts is as follows: the metal salts are soluble metal salts, specifically including iron salts, cobalt salts, nickel salts, copper salts and manganese salts, preferably ferric chloride, cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride and manganese chloride tetrahydrate. The molar ratio of the soluble metal salts is preferably an equimolar ratio, which is conducive to reducing the generation of metal oxide impurities and ensuring the formation of single-phase high entropy oxides. The solvent of this step is the same as the solvent in the graphene treatment process, preferably water. The ultrasound refers to the use of an ultrasonic cleaning machine to disperse the metal salt solution. The dispersion time does not need to be too long. It is only necessary to mix the soluble metal salt in the solvent. The ultrasound time is 3 to 10 minutes, preferably 3 to 5 minutes, for example 6 minutes. The corresponding metal ion concentration in each soluble metal salt solution is 0.2 to 0.6 mol / L, for example 0.2 mol / L.

[0038] S2, adding the metal salt solution to the graphene suspension, adding urea and stirring, and then pre-treating the resulting mixed solution to obtain a precursor powder. In this step, the mass ratio between graphene, metal salt (metal ion) and urea is controlled to be 1: (1-10): (5-50), preferably 1: (2-10): (5-30). Using different ratios will prepare reduced graphene oxide loaded high entropy oxides with different geometric structures, for example, the mass ratio between the graphene, metal ions and urea satisfies 1: 2.3: 7.2, and the prepared high entropy oxide presents a tetrahedral structure with a particle size of 50nm; the mass ratio between the graphene, metal ions and urea satisfies 1: 4.6: 14.4, and the prepared high entropy oxide presents an octahedral structure with a particle size of 100nm; the mass ratio between the graphene, metal ions and urea satisfies 1: 9.2: 28.8, and the prepared high entropy oxide presents a truncated octahedral structure with a particle size of 200nm. When the mass ratio between graphene, metal salt and urea meets 1:9.2:28.8. When the mass ratio between graphene, metal salt and urea meets 1:9.2:28.8, based on the total mass of reduced graphene oxide loaded with high entropy oxide, the mass proportion of high entropy oxide is 30%, and the wave absorption performance is excellent. When adding urea, the stirring speed is 500r / min~800r / min, for example 600r / min, and the stirring time is 1~2h, for example 2h. Pretreatment includes centrifugation, washing and freeze-drying in sequence. The specific pretreatment steps are:

[0039] (1) The mixed solution is centrifuged and washed for multiple times to obtain a precipitate. The solvent is removed by centrifugation, the centrifugal speed is 5000-10000 rpm, preferably 5000-8000 rpm, more preferably 6000 rpm; the centrifugal time is 5-10 minutes, preferably 8 minutes. After centrifugation, the washing agent is any one of deionized water and anhydrous ethanol, preferably deionized water. In this step, the number of centrifugal washings is 2-4 times, preferably 3 times. During the washing process, the metal ions and chloride ions anchored on the graphene surface are washed away, so the number of washings cannot be too little or too much. Too little will result in the excess metal ions not being washed clean, and too much will result in the excess metal ions anchored on the graphene surface being washed away.

[0040] (2) freeze-drying the precipitate to obtain a precursor powder. The freeze-drying time is 24 to 72 hours, preferably 25 to 50 hours, and more preferably 36 hours, wherein the precursor is brown-green in color.

[0041] S3, subjecting the precursor powder to plasma jet treatment to obtain a high entropy oxide loaded with reduced graphene oxide. The precursor powder is treated with a plasma jet to activate graphene to reduce graphene oxide; at the same time, five metal ions are nucleated and eutectic to form a high entropy oxide. The treatment time of the plasma jet is 0.5 to 10 s, preferably 0.8 to 2.4 s, for example 30 A, and the current is 30 to 60 A, preferably 30 to 40 A, for example 0.8 s. During the plasma jet treatment, if the current used is too small and / or the time is too short, the high entropy oxide cannot be completely eutectic, and metal oxide impurities appear; if the current used is too large and / or the time is too long, the lightweight graphene component will be instantly oxidized at high temperature, and no product will remain. During the plasma jet treatment, the gas used is an inert gas such as nitrogen or argon, and the inert gas is mainly used to generate plasma and protect graphene from oxidation at extremely high temperatures. The gas flow rate of the gas is 200 to 500 ml / min, preferably 500 ml / min. When the gas flow rate is too small, the plasma jet cannot completely crystallize and eutectic the high entropy oxide; but when the gas flow rate is too large, the plasma jet ionization is too strong, resulting in the gasification of graphene and no product remaining. The conductivity of the prepared high entropy oxide is 0.45-10S / cm.

[0042] In addition, the second aspect of the present invention provides a high entropy oxide supported by reduced graphene oxide, the high entropy oxide is obtained by the preparation method of the high entropy oxide supported by reduced graphene oxide described in any one of the above descriptions, the particles of the high entropy oxide are uniformly supported on the surface of the reduced graphene oxide without particle agglomeration, and the particle size of the high entropy oxide is 50 to 250 nm. The structure of the high entropy oxide is a polyhedron, and the polyhedron includes a tetrahedron, an octahedron, and a truncated octahedron.

[0043] Furthermore, the high entropy oxide includes iron, cobalt, nickel, manganese and copper, which are derived from soluble metal salts, and the high entropy oxide particles account for 10% to 30% of the total mass ratio. That is, based on the mass of the high entropy oxide loaded on the reduced graphene oxide, the high entropy oxide loading is 10 to 30 wt%.

[0044] Furthermore, the electrical conductivity of the high entropy oxide is 0.45-10 S / cm, the minimum reflection loss RLmin is -57 dB at room temperature, and the maximum effective absorption bandwidth (EAB) is 4.13 GHz.

[0045] In addition, the third aspect of the present invention provides the application of the high entropy oxide supported by reduced graphene oxide as described in any one of the above descriptions or the high entropy oxide supported by reduced graphene oxide prepared by the preparation method described in any one of the above descriptions in the electromagnetic field.

[0046] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0047] Example 1

[0048] Weigh 25 mg of Shanghai Aladdin graphene, place it in 50 mL of water, and use an ultrasonic cell disruptor to ultrasonicate for 60 minutes at a power of 400 W to obtain a graphene suspension; use water to prepare five metal salt solutions of ferric chloride, cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride, and manganese chloride tetrahydrate, each with a metal cation concentration of 0.2 mol / L, and ultrasonicate each metal salt solution in an ultrasonic cleaner for 6 minutes.

[0049] Take 4 ml of each metal salt solution and add it to the 0.5 mg / mL graphene suspension, and add 720 mg of urea. The mass ratio between graphene, metal salt and urea satisfies 1:9.2:28.8, where the metal salt is the total mass of five metal ions Fe, Co, Ni, Cu, and Mn, each metal ion is 1 mM, and the total mass of the metal salt is 230 mg. Stir magnetically for 2 hours at a stirring speed of 600 r / min. Then centrifuge and wash the mixed solution, repeat 3 times, and place it in a freeze dryer to dry for 36 hours to obtain a brown-green precursor powder. Place the precursor powder directly below the plasma jet and perform plasma jet treatment under the following conditions to obtain a high entropy oxide loaded with reduced graphene oxide: the gas used is argon (gas flow rate is 500 ml / min), the current is 30 amps, and the treatment time is 0.8 seconds. The structure of the high entropy oxide supported by reduced graphene oxide obtained in Example 1 is a truncated octahedron, which accounts for 30wt% of the total mass ratio. The conductivity of the high entropy oxide supported by reduced graphene oxide is 0.48S / cm. Figure 4 shown.

[0050] The high entropy oxide supported by the reduced graphene oxide was tested for electromagnetic wave absorption performance as follows. The test process is: the reduced graphene oxide supported high entropy oxide and molten paraffin are mixed in a mass ratio of 3:7, and then pressed into a coaxial ring-shaped sample in a mold, the outer diameter of the ring is 7.01 mm, and the inner diameter is 3.04 mm. The relative complex dielectric constant and relative complex magnetic permeability of the reduced graphene oxide supported high entropy oxide are tested in the range of 2-18 GHz using a network vector analyzer, and the electromagnetic wave absorption reflection three-dimensional map is obtained by the following formula, and the formula is as follows:

[0051]

[0052] In formula (1) and formula (2), Z0 is the vacuum characteristic impedance, Z in represents the normalized input impedance of the electromagnetic absorption material, εr and μ r Respectively represent the relative complex dielectric constant and relative complex magnetic permeability of the material, f represents the frequency of the electromagnetic wave, d represents the thickness of the electromagnetic absorption material, c represents the speed of light in a vacuum, Tanh represents the hyperbolic tangent function, and j represents an imaginary number. The electromagnetic absorption loss and effective bandwidth obtained are shown in the figure Figure 5 As shown, it can be seen that the reduced graphene oxide loaded with high entropy oxide has excellent electromagnetic absorption performance, the minimum reflection loss RLmin is -57dB, and the maximum effective absorption bandwidth (EAB, the effective absorption bandwidth is the frequency band with reflection loss less than -10dB) is 4.13GHz. By comparing with the electromagnetic absorption performance diagram of Example 2 ( Fig. 9 ) and the electromagnetic absorption performance diagram of Example 3 ( Fig.13 ) are compared and it is found that Example 1 has the strongest electromagnetic absorption reflection loss, and Example 1 is the optimal example. Figure 1 This is a transmission electron microscope image of the reduced graphene oxide loaded with high entropy oxide. The scale length is 100nm. It can be seen that the geometric structure of the high entropy oxide is a truncated octahedron, and its particle size is 200nm. Figure 2 This is a high-resolution electron microscopy image of the reduced graphene oxide loaded with high entropy oxide. Figure 2 The morphology and lattice fringes of a single truncated octahedron were characterized. The lattice fringes of 0.484 nm represented the (111) crystal plane of the crystal, indicating the successful preparation of the high entropy oxide. Figure 3 The energy spectrum of the reduced graphene oxide loaded with high entropy oxide is shown. Figure 3 It can be seen that the metal elements Fe, Co, Ni, Cu, and Mn are evenly distributed in the crystal, without segregation or separation of elements, which further proves the successful synthesis of high entropy oxides. Figure 4 The conductivity comparison diagram of the obtained reduced graphene oxide loaded high entropy oxide and Example 2 and Example 3 is shown, Figure 5 The electromagnetic absorption loss diagram of the prepared reduced graphene oxide loaded with high entropy oxide is shown.

[0053] Example 2

[0054] Weigh 25 mg of Shanghai Aladdin graphene, place it in 50 mL of water, and use an ultrasonic cell disruptor to ultrasonicate for 60 minutes at a power of 400 W to obtain a suspension; use water to prepare five metal salt solutions of ferric chloride, cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride, and manganese chloride tetrahydrate, respectively, with the metal cation concentration of 0.2 mol / L, and ultrasonicate the metal salt solutions in an ultrasonic cleaner for 6 minutes.

[0055] Take 2 ml of each metal salt solution and add it to the 0.5 mg / mL graphene suspension, and add 360 mg of urea. The mass ratio of graphene, metal salt and urea is 1:4.6:14.4. Stir magnetically for 2 hours at a stirring speed of 600 r / min. Then centrifuge and wash the mixture, repeat 3 times, and place it in a freeze dryer to dry for 36 hours to obtain a brown-green precursor powder.

[0056] The precursor powder is placed directly under the plasma jet and subjected to plasma jet treatment under the following conditions to obtain reduced graphene oxide loaded with high entropy oxide: the gas used is argon (gas flow rate is 500 ml / min), the current is 30 A, and the treatment time is 0.8 s.

[0057] The high entropy oxide in the prepared reduced graphene oxide supported high entropy oxide has an octahedral geometric structure, which accounts for 21wt% of the total mass ratio, and the conductivity of the reduced graphene oxide supported high entropy oxide is 2.5S / cm. Figure 4 The reduced graphene oxide loaded with high entropy oxide was tested for electromagnetic wave absorption performance according to the operation in Example 1. The test process of Example 2 is the same as that of Example 1. Figure 6 The transmission electron microscope image of the prepared reduced graphene oxide loaded with high entropy oxide is shown. It can be seen that the geometric structure of the high entropy oxide is octahedral, and its particle size is 100nm. Figure 7 The high-resolution electron microscopy image of the reduced graphene oxide loaded with high entropy oxide is shown. Figure 7 The morphology and lattice fringes of a single octahedron were characterized. The lattice fringes of 0.484 nm represent the (111) crystal plane of the crystal, indicating the successful preparation of high entropy oxide. Figure 8 The energy spectrum of the reduced graphene oxide loaded with high entropy oxide is shown. Figure 8 It can be seen that metal elements such as Fe, Co, Ni, Cu, and Mn are evenly distributed in the crystal, without segregation or separation of elements. Fig. 9 The electromagnetic absorption loss diagram of the prepared reduced graphene oxide loaded with high entropy oxide is shown. It can be seen that the minimum reflection loss RLmin is -18.1dB and the maximum effective absorption bandwidth is 5.1GHz.

[0058] Example 3

[0059] Weigh 25 mg of Shanghai Aladdin graphene, place it in 50 mL of water, and use an ultrasonic cell disruptor to ultrasonicate for 60 minutes at a power of 400 W to obtain a suspension; use water to prepare five metal salt solutions of ferric chloride, cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride, and manganese chloride tetrahydrate, respectively, with the metal cation concentration of 0.2 mol / L, and ultrasonicate the metal salt solutions in an ultrasonic cleaner for 6 minutes.

[0060] Take 1 ml of each metal salt solution and add it to a 0.5 mg / mL graphene suspension, and add 180 mg of urea. The mass ratio of graphene, metal salt and urea meets 1:2.3:7.2. Stir magnetically for 2 hours at a stirring speed of 600 r / min. Thereafter, the mixed solution is centrifuged and washed, and after repeating 3 times, it is placed in a freeze dryer and dried for 36 hours to obtain a brown-green precursor powder. The precursor powder is placed directly below the plasma jet and subjected to plasma jet treatment under the following conditions to obtain reduced graphene oxide loaded with high entropy oxide: the gas used is argon (gas flow rate is 500 ml / min), the current is 30 amps, and the treatment time is 0.8 seconds. The high entropy oxide geometric structure of the reduced graphene oxide loaded with high entropy oxide obtained in Example 3 is a tetrahedron, which accounts for 12 wt% of the total mass ratio, and the conductivity of the reduced graphene oxide loaded with high entropy oxide is 10.02 S / cm, such as Figure 4 shown.

[0061] The reduced graphene oxide loaded with high entropy oxide was tested for electromagnetic wave absorption performance according to the operation in Example 1. The test process of Example 3 is the same as that of Example 1. Fig.10 The transmission electron microscope image of the prepared reduced graphene oxide loaded with high entropy oxide is shown. It can be seen that the geometric structure of the high entropy oxide is tetrahedral, and its particle size is 50nm. Fig.11 The high-resolution electron microscopy image of the reduced graphene oxide loaded with high entropy oxide is shown. Fig.11 The morphology and lattice fringes of a single tetrahedron were characterized. The lattice fringes of 0.486 nm represent the (111) crystal plane of the crystal. Fig.12 The energy spectrum of the reduced graphene oxide loaded with high entropy oxide is shown. Fig.12 It can be seen that metal elements such as Fe, Co, Ni, Cu, and Mn are evenly distributed in the crystal, without segregation or separation of elements. Fig.13 The electromagnetic absorption loss diagram of the prepared reduced graphene oxide loaded with high entropy oxide is shown. It can be seen that the minimum reflection loss RLmin is -7dB and the maximum effective absorption bandwidth is 0GHz.

[0062] The present invention proposes a high entropy oxide supported by reduced graphene oxide, a preparation method and an application thereof. In the preparation method, five metal salts and urea are placed in a graphene dispersion, and the reduced graphene oxide supported high entropy oxide is obtained by centrifugation, freeze drying and plasma jet in sequence. In the obtained reduced graphene oxide supported high entropy oxide, the high entropy oxide with a geometric structure is uniformly loaded on the surface of the reduced graphene oxide, which enhances the multiple scattering of electromagnetic waves. The reduced graphene oxide supported high entropy oxide has the advantages of excellent impedance matching and strong wave absorption loss ability, and has huge market demand and broad application prospects in the fields of consumer electronics, medical equipment, and vehicle energy. The present invention has the following advantages:

[0063] (1) The high entropy oxide supported by reduced graphene oxide provided by the present invention has the advantages of multi-crystalline surface scattering, excellent impedance matching and strong wave absorption loss ability, and has broad application prospects in the electromagnetic fields of consumer electronics, new energy vehicles and military weapons.

[0064] (2) The high entropy oxide supported by reduced graphene oxide provided by the present invention is a polyhedral structure, and the high entropy oxide includes tetrahedrons, octahedrons and truncated octahedrons. The polycrystalline face structure enhances the multiple scattering of electromagnetic waves.

[0065] (3) The present invention provides a high entropy oxide with a particle size between 50 and 250 nm loaded on the surface of reduced graphene oxide, the impedance matching is enhanced, and the conductivity of the composite material is between 0.45 and 10 S / cm.

[0066] (4) The preparation method provided by the present invention utilizes a plasma jet to promote the entropy forming process of metal elements and the transformation of graphene into reduced graphene oxide; at the same time, the extremely fast heating rate enables the reduced graphene oxide to retain a thin layer of microporous structure, thereby avoiding high-temperature gasification under oxygen.

[0067] (5) In the preparation method provided by the present invention, the duration of plasma heating is in the range of 0.5 to 10 s, which improves the preparation efficiency of high entropy oxides and facilitates industrial production.

[0068] Obviously, the described embodiments are part of the embodiments of the present invention, but not all of them. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. It should be understood that the above-mentioned specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation on the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the scope of protection of the present invention. In addition, the claims attached to the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries. The present invention is described above with reference to the embodiments of the present invention. However, these embodiments are for illustrative purposes only, not for limiting the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents. Without departing from the scope of the present invention, a variety of substitutions and modifications can be made by those skilled in the art, and these substitutions and modifications should fall within the scope of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and modifications may be made to the embodiments of the present invention without departing from the spirit and scope of the present invention. Obviously, the above embodiments are merely examples for clear description and are not limitations on the embodiments. For those of ordinary skill in the art, other different forms of changes or modifications may be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived therefrom are still within the scope of protection created by the present invention.

Claims

1. A method for preparing a high entropy oxide supported by reduced graphene oxide, characterized in that: The following steps are involved: S1, dissolving graphene and metal salt in respective solvents and subjecting them to ultrasonic treatment to obtain metal salt solution and graphene suspension respectively; S2, adding the metal salt solution to the graphene suspension, adding urea and stirring, and then pretreating the resulting mixed solution to obtain a precursor powder; S3, subjecting the precursor powder to plasma flow treatment to obtain a high entropy oxide supported by reduced graphene oxide.

2. The method for preparing a high entropy oxide supported by reduced graphene oxide according to claim 1, characterized in that: In the step S2, the mass ratio of graphene, metal salt and urea is controlled to be 1:(1-10):(5-50).

3. The method for preparing a high entropy oxide supported by reduced graphene oxide according to claim 2, characterized in that: The metal salt is a soluble metal salt, including iron salt, cobalt salt, nickel salt, copper salt and manganese salt.

4. The method for preparing a high entropy oxide supported by reduced graphene oxide according to claim 1, characterized in that: The pretreatment includes centrifugation, washing and freeze-drying in sequence.

5. The method for preparing a high entropy oxide supported by reduced graphene oxide according to claim 1, characterized in that: In the step S3, the treatment time of the plasma jet is 0.5 to 10 seconds, and the current is 30 to 60A.

6. The method for preparing a high entropy oxide supported by reduced graphene oxide according to claim 1, characterized in that: The electrical conductivity of the high entropy oxide is 0.45-10 S / cm.

7. A high entropy oxide supported by reduced graphene oxide, characterized in that The high entropy oxide is obtained by the preparation method of the high entropy oxide supported by reduced graphene oxide according to claims 1-6, and the structure of the high entropy oxide includes tetrahedron, octahedron and truncated octahedron.

8. The high entropy oxide supported by reduced graphene oxide according to claim 7, characterized in that: The particle size of the high entropy oxide is 50 to 250 nm.

9. The high entropy oxide supported by reduced graphene oxide according to claim 7, characterized in that The high entropy oxide comprises iron, cobalt, nickel, manganese and copper, and the high entropy oxide particles account for 10% to 30% of the total mass.

10. Application of the high entropy oxide supported by reduced graphene oxide prepared by the preparation method according to any one of claims 1 to 6 or the high entropy oxide supported by reduced graphene oxide according to any one of claims 7 to 9 in the electromagnetic field.

Images